Progesterone treatment in early pregnancy
Why progesterone?
Progesterone is a hormone made by the eggshell left behind after an egg is released - known as a corpus luteum. Progesterone is a crucial hormone in early pregnancy, playing several vital roles in establishing and maintaining a healthy pregnancy. Some of these include:
Preparing the endometrium: Progesterone helps thicken the lining of the uterus (endometrium), creating a supportive environment for the fertilised egg to implant and grow.
Supporting implantation: Progesterone promotes the formation of blood vessels and the secretion of nutrients in the endometrium, which are essential for the developing embryo.
Maintaining pregnancy: Once the fertilised egg has been implanted, progesterone helps to maintain the pregnancy by preventing uterine contractions that could dislodge the developing embryo.
Adjusting a woman’s immune system: Progesterone contributes to creating a ‘tolerant’ environment in the uterus, preventing the mother's immune system from attacking the embryo as a foreign body.
Developing the placenta: Progesterone is involved in the growth and development of the placenta, a critical structure that supplies oxygen and nutrients to the fetus and removes waste products.
Overall, progesterone is an essential hormone for establishing and maintaining a healthy pregnancy, particularly during the early stages when the foundations for fetal development are being laid. Insufficient progesterone levels can contribute to difficulties in conceiving, implantation failure, or early pregnancy loss. For these reasons, it’s not surprising that a lot of research has been done to see if progesterone treatment might be helpful.
Threatened miscarriage
The first situation to consider is when you’ve experienced bleeding in early pregnancy. In medical terminology, this is called a threatened miscarriage. The best evidence we have to date is that it depends on several factors - the most important of which is your pregnancy history. Research tells us that if you have experienced a miscarriage before, progesterone support after early pregnancy bleeding next time around leads to a five percent (5%) higher likelihood of live birth in that pregnancy. There was no benefit for women who hadn’t experienced a miscarriage before.
Progesterone doesn’t work when you’re trying to get pregnant; for most people, it doesn’t help if you don’t have bleeding. We will cover its use in women who experienced more than one miscarriage (but with no bleeding) below.
Previous miscarriage - but no bleeding
If you’ve had one or two miscarriages before, progesterone treatment may increase your chances of a successful pregnancy by approximately 5%. If you have had 3 or more miscarriages, taking progesterone in early pregnancy may increase your chances of having a successful pregnancy by around 15%.
How do I take progesterone?
Progesterone is not easily absorbed in tablet form, and the most common way to receive it is via pessaries inserted into the vagina. This is how it was taken in the research that found it to be beneficial. The dose of progesterone is as follows:
Early pregnancy bleeding, with a previous miscarriage: 400mg, twice daily. Start once an ectopic pregnancy has been ruled out by ultrasound.
Previous miscarriage, with no current bleeding: the dose used has varied in research studies, but 200-400mg, twice daily. Start as soon as you have a positive pregnancy test and preferably before 6 weeks gestation
When should you stop progesterone if you start it for these reasons?
The Clinical Excellence guideline from the UK states 16 weeks, based upon one of the research studies. When we look back at the benefit that was achieved, it was completed by 12 weeks gestation. We know that from 9 weeks, the placenta starts to take over pregnancy support from corpus luteum progesterone. In general, I prefer to give the minimum dose necessary for any drug used during pregnancy, and I believe that 12 weeks is a good balance of safety and treatment benefits. Others have recommended this, too (see Duncan WC, below).
Below is a video which explains how to use progesterone. There are two main progesterone pessary options in Australia: Utrogestan and Oripro. Both are suitable and are used the same way.
If you would like to discuss your unique situation or have received inconsistent advice about early pregnancy care, please make an appointment to discuss your treatment with Dr Tucker.
Evidence and links
UK National Institute of Clinical Excellence guideline: threatened miscarriage and progesterone
St Thomas’s Hospital, London. Patient information sheet: Early pregnancy bleeding and progesterone
Did the NICE guideline for progesterone treatment of threatened miscarriage get it right? Duncan WC. Reprod Fertil. 2022 Apr 1; 3(2): C4–C6 link to article